Destructive distillation of wood



Nov. 3, 1925- 1,559,994

D. P: SHAW DESTRUCTIVE DISTILLATION 0F WOOD Filed D90. 21, 1922 PatentedNov. 3, 1925.

UNITED STATES DUNCAN P, SHAVT, OIE FAYETTEVILLE, NORTH CAROLINA.

DESTRUGTIVE DISTILLATIO'N 0F WOOD.

Application filed December 21, 1922.

T 0 all whom it may concern:

Be it known, that I, DUNCAN P. SHAW, a citizen of the United States, anda resident of Fayetteville, county of Cumberland, and State of NorthCarolina, have invented a new and useful Improvement in DestructiveDistillation of Wood, of which the following is a specification.

This invention relates to an improvement in the process of extractingfrom burning pine Wood the vapors emanating therefrom for producingturpentine, and other products from pine lightwood.

The invention relates more particularly to the extracting of the tar andthe turpentine from lightwood which is burned in a kiln. It has beencustomary for many years to extract tar from the pine lightwood by meansof kilns which are constructed of pine straw and earth. A trench ortunnel is formed in the ground which slopes gradually in length and atthe lower and shorter end of the trench or tunnel a pit or receptacle isprovided for catching the tar which drains from the tunnel through alongitudinal groove or ditch. The wood is laid generally lengthwise ofthe tunnel and the wood is of various lengths, the length of the woodnot being material. After the wood has been piled throughout the lengthof the tunnel the pile of wood is completely covered with pine straw,sand or clay so that the pile is completely covered and closed at thelower end. This covering prevents air currents and keeps a fire which ison the back end from'drawing through and consuming the wood withoutproducing tar. With kilns of this type the vapors which are produced bythe burning and the destructive distillation of the wood have heretoforebeen lost as these vapors have been allowed to be drawn by the fire andconsumed, and it is the purpose of this invention to recover thesevapors which are produced by the destructive distillation of the wood.

In the accompanying drawing an apparatus is disclosed in connection withaki-ln as above described which may be employed for the recovery of thevapors produced by the destructive distillation, in which:

Figure l is a diagrammatical view in plan of the kiln and an apparatusfor drawing the vapors from the kiln;

Figure 2 is a transverse vertical sectional view of one of the vaporcollecting boxes;

Figure 3 is a detail view partially in ele- Serial No. 608,384.

of one of kiln and spaced at a suitable distance from each other are aplurality of vapor collecting boxes 6. These boxes or outlet conduitsare preferably constructed of wood and provided with a plurality ofperforations in three sides as indicated at 7, so that the vapors mayenter the boxes. These boxes are laid crosswise of the kiln and upon orin the piled wood and have one end projecting through a side of thekiln. A pipe 8 is connected to these various boxes 6 by branch pipes 9,9, each branch pipe being provided with a valve 10 for closing the samewhereby the branch pipe may be closed after the fire has consumed thewood in the vicinity of the vapor box.

The pipeS leads" to a suitable condenser 10 and leadingfrom thecondenser is a pipe 11 to which is connected a pipe 12 through which thecondensed vapors are discharged into a suitable container. An upright,pipe 13 is connected to the pipe 11 and located at the upper end ofthispipe l3 is inserted a steam or air pipe-14. This pipe le whiehdelivers air or steam to the pipe produces a suction through the pipes13, '11, condenser 10 and pipes 8 and 9 for drawing the vapors from thevapor boxes 6 into the condenser from which condenser the condensedvapors are delivered to the pipe 12.

duced by the distilling of the wood and' these vapors are collected inthe vapor boxes 6 j 1 It is to be understood that this form of kiln andform of condenser with its various connections may be substituted byother forms that may be foundmore feasible for the type ofkiln orconditions of operations.

In the burning of a kiln of the character set forth, the fire is startedat the large or back end of the kiln, and as the pile of wood is coveredwith sand or clay and pine straw, the combustion of the wood is slow,

so that there is a gradual and progressive burning of the wood, from oneend of the kiln to the other in a horizonal direction. That is, the fireis of suflicient' intensity to consume the wood, but not to that degreethat the wood would be consumed rapidly and thereby destroy theproducts, such as tar and like vapors that will issue from the wood whenburned slowly. As the wood is consumed, the vapors emanating therefromwill be collected by the vapor box 6, which is closest to the burningwood, and these vapors will be drawn from the box 6 through the pipes 8and 9' to the condenser. When the wood is consumed up to the vapor box,or the attendant believes that a particular box should be cut off, dueto the proximity of the fire, the valve in the pipe 9,'will be shut off,and the vapors will then be collected inthe next or adjacent boxes 6. Byclosing the valve 10, of the box which is no longer in use, or can beused,

either due to the fact that the box has been consumed by the fire, orthat the fire has progressed beyond the box, the vapors are preventedfrom escaping through the pipe leading to that particular box or boxes,or the drawing into the pipe line other vapors or gases not desired,such as gases of combustion which contain no tarry vapors to be mixedwith, the vapors recovered from the burning wood.

In some instances it may be found advisable to employ steam during thecombustion of the wood, and in such cases, steam pipes 16. have beenprovided, so that steam may be: injected into the heated zone in advanceor-adjacent to the zone of the burning wood, by opening the valve on thepipe 16, and thereby causing the steam to assist in vaporizing the tarryproducts produced by the heat of the burning wood in the combustionzone. As soon as a pipe 16 is no longer needed by reason of theconsumption of the kiln and pile, that pipe will be cut off from themain supply pipe 15, by the valve in the pipe 16.

It, will be readily understood from the foregoing'that provision-hasbeen made for collecting the vapors produced in the destructivedistillation of wood ina kiln which destructive distillation is causedby heat produced by burning-part of the wood, wherein the fire comes. indirect contact and consumes the wood, and drawing oif the tarry vaporsfrom a distilling zone adjacent to, the, combustion ZOIlQ. to a suitablecondenser. from which the condensed vapors may betakenand treated.

Heretofore,these-, vapors have been. lost and only the tar has beenextracted from the wood, except in such cases where retorts areemployed. The excessive costs attendant in the employment of a retort,and the location of the material, is such that it is often prohibitiveto employ a retort, so that the operator has heretofore simply burnedhis wood in a kiln and recovered the tar, and allowed the vapors to beconsumed in the fire and lost. With this invention, turpentine and likevapors as well as tar vapors are recovered from the distillation zonewithout being commingled with the combustion gases from the combustion.zone of burning wood.

Having described my invention what I claim as new and desire to secureby Letters Patent is:

1. The process of destructive distillation of wood, consisting in.progressively burning a mass of such woodfrom one end to the other of akiln in a substantially horis zontal direction, and in withdrawing thedistilled vapors from. a zone in advance of said progressively burningportion, and sub,- stantially avoiding the intermixing with, thedistilled vapors of any gases of combustion which contain. no tarvapors. r

2. The process of destructive distillation of wood, consisting in slowlyand gradually burning a mass of such wood progressively from one endto'the other of a kiln. in a substantially horizontal direction,v and inwithdrawing the distilled vapors from a zone in advance of the burningportion, and substantially avoiding the intermixing with thedistilledvapors of any gases of combustion which contain no vapors.

3. The process of destructive distillation of wood, consisting in slowlyand gradually burning a mass of such. wood progressively from one end tothe other of a' kiln, in a substantially horizontal direction,subjecting the heated wood in advance of the burning wood to the, actionof steam for distilling the distillates, and inwithdrawing the distilledvapors from a zone-in advance of the burning portion, and substantiallyavoiding the intermixing with the distilled v vapors of any gases ofcombustion which contain notar= vapors.

4:. The process of-destructive distillation of wood, consisting inprogressively burning a mass of such wood from one end to the other of akiln in 'a substantially horizontal direction, and in withdrawing thedistilled vapors from said mass successively in advance of the burningportion, and substantially avoiding-the intermixing with the distilledvapors of any gases of combustion which contain no tar vapors.

DUNCAN P. SHAW;

